Abstract

By using the most recent version (1900–2007) of the Centennial Earthquake Catalog, we examine the properties of the global seismicity. Natural time analysis reveals that the fluctuations of the order parameter of seismicity exhibit for at least three orders of magnitude a characteristic feature similar to that of the order parameter for other equilibrium or non-equilibrium critical systems—including self-organized critical systems. Moreover, we find non-trivial magnitude correlations for earthquakes of magnitude greater than or equal to 7.

Received 05 December 2011Accepted 10 April 2012Published online 09 May 2012

Lead Paragraph: Earthquakes exhibit complex correlations between space, time, and magnitude M and as such they present a protype example for a complex time series. Usually, however, the study of earthquakes is focused on some specific seismic active region. One reason for this might be the fact that there are only a few well-established global seismicity databases. Another reason might be the fact that there is no unanimous opinion in the seismological community whether earthquakes in different places of the globe are correlated. In order to clarify the latter, in the present study, we make use of the most recent version of the Centennial Earthquake Catalog, which is a global catalog of locations and magnitudes of instrumentally recorded earthquakes from 1900 to September 2007. We apply the recently introduced method of natural time analysis, which enables the detection of long-range temporal correlations even in the presence of heavy tails, and find that the global seismicity exhibits features similar to that of other equilibrium or non-equilibrium critical systems. Moreover, we show that there exist non-trivial magnitude correlations in the global seismicity for earthquakes of magnitude greater than or equal to 7. This result could be interpreted as indicating that the whole of the solid Earth crust should be considered as a single complex system.